Generally, a construction machine such as a hydraulic excavator is constituted by an automotive lower traveling structure, an upper revolving structure which is swingably mounted on the lower traveling structure, and a working mechanism liftably mounted on the front side of the upper revolving structure. An engine for driving a hydraulic pump is mounted on a rear portion of a revolving frame of the upper revolving structure, and an exhaust gas purifying device for purifying exhaust gas by removing harmful substances in the exhaust gas is provided in an exhaust pipe of the engine.
Further, as an exhaust gas purifying device which is provided in a hydraulic excavator, a device is known which has an oxidation catalyst for removing by oxidation carbon monoxide (CO) and hydrocarbons (HC) in the exhaust gas, a particulate matter removing filter (generally called a diesel particulate filter, abbreviated as DPF) for capturing and removing particulate matter (PM) in the exhaust gas (Patent Literature 1: Japanese Patent Laid-Open No. 2003-120277 A).
The exhaust gas purifying device according to this Patent Literature 1 is largely constituted by connecting in series an upstream cylinder connected to the exhaust pipe of an engine, a downstream cylinder which is disposed downstream of the upstream cylinder and from which exhaust gas is discharged, and an intermediate cylinder provided between the upstream cylinder and the downstream cylinder. The aforementioned oxidation catalyst, particulate matter removing filter, and the like are accommodated in such as the intermediate filter.
Here, as for the oxidation catalyst provided in the exhaust gas purifying device, the exhaust gas needs to be adjusted to a predetermined temperature in order to effect appropriate oxidation treatment. In addition, since the captured particulate matter becomes clogged due to the deposition of the captured particulate matter, the captured particulate matter is removed by burning it at a stage when a predetermined amount has accumulated.
For this reason, the exhaust gas purifying device is provided with a temperature detector for detecting the temperature of the exhaust gas flown toward the oxidation catalyst, a temperature detector for detecting the temperature of the exhaust gas flown toward the particulate matter removing filter, and a pressure detector for detecting the front and rear pressures of the particulate matter removing filter through respective conduits to measure the amount of particulate matter accumulated (Patent Literature 2: Japanese Patent Laid-Open No. 2005-256627 A).
The two temperature detectors and the pressure detector which are provided in the exhaust gas purifying device are adapted to output the detected temperature and the detected pressure to a controller, respectively, and harnesses linked to the controller are connected to connector portions provided in the respective temperature detectors and the pressure detector.
Thus, in the exhaust gas purifying device in accordance with Patent Literature 2, since two temperature detectors and one pressure detector are provided, when the exhaust gas purifying device is assembled to the vehicle body side, the controller side harnesses must be connected to the connector portions of three detectors in total. However, since the respective detectors are disposed in a dispersed manner on the exhaust gas purifying device in its entirety, much time is necessary in the connection operation of the harnesses. Since numerous equipments, piping, and the like are present particularly in the surroundings of the engine where the exhaust gas purifying device is provided, it is difficult to perform the operation by avoiding such equipments, piping, and the like, so that there is a problem in that assembly workability declines.
Moreover, the conduits disposed on the outer peripheral sides of the respective cylinders unfavorably serve as obstacles when the cylinders are separated and moved in order to perform the cleaning operation of the particulate matter removing filter. For this reason, in cases where the cleaning operation of the particulate matter removing filter is carried out, the conduits must be removed, so that there is a problem in that the operational efficiency deteriorates.